William was
pincerna (cup bearer or butler) to
Malcolm IV and
William the Lion, and he is also styled as such in some of the early charters of William the Lion, and in a charter that he himself granted in 1171. During the years 1173-74, three of
Henry II of England's sons and his wife,
Eleanor of Aquitaine, rebelled against him. In 1174, believing Henry II to be distracted by the fighting in France, William the Lion attempted to regain
Northumberland for Scotland. He was captured at the
Second Battle of Alnwick and taken to Henry in Falaise in Normandy. In order to regain his freedom, in December 1174, he had to sign the punitive
Treaty of Falaise. One of the last provisions was that William the Lion had to send twenty-one hostages to England to ensure compliance. One who went in that role was William de Haya, his butler. In August 1175, the Treaty of Falaise was ratified at
York and William the Lion and his brother, David, having paid homage to
Henry II of England for
Scotland and
Galloway, were allowed to return to Scotland. According to J. C. D. Hay, William de Haya was also allowed to return to Scotland at that time. William was one of the ambassadors sent in 1199 by William the Lion to the newly crowned King
John of England to try to have his lost patrimony of Northumberland and
Cumberland returned to Scotland. King William offered to swear fealty to King John if this demand was granted. ==The first feudal Baron of Erroll==